The most common embodiment of automatic transmissions in passenger cars is the so-called torque converter transmission that differs from conventional and automatic shifting gearboxes primarily by a shifting process that is free from breaks in the traction force. Such automatic transmissions in passenger cars usually have a hydraulic torque converter as a starter coupling and are comprised essentially from several plate couplings and also a combination of several free-running wheels and planetary gears. All of the shifting and coupling processes are performed via the plate couplings that produce the non-positive fit connection of the individual planetary gear stages to the input and output shafts of the automatic transmission.
Because considerable axial forces also act between the gearbox components during the individual shifting processes due to the usually helical planet wheels of the planetary gear train, to avoid friction losses and reduced efficiency, the individual coupling and planet-wheel carriers are each supported, depending on the shift gear number, by up to 17 axial needle bearings relative to each other. In special cases, individual coupling or planet wheel carriers must be supported in the axial direction even on both sides against two additional adjacent gearbox components. For supporting the planet-wheel carrier against the adjacent sun wheel of a planetary gear train on one side and also against an adjacent belt pulley on the other side, an axial bearing assembly is known, for example, from DE 60 2005 001 069 T2, which is made essentially from two conventional axial needle bearings, with the circular ring-shaped side wall of the planet-wheel carrier being arranged between these axial needle bearings. Here, each of the two axial rolling bearings has, in a known way, a first ring-shaped bearing disk adjacent to one of the axial sides of the planet-wheel carrier and a second ring-shaped bearing disk mounted on the adjacent sun wheel or on the adjacent belt pulley, with each bearing disk being made from one thinner steel plate and one thicker steel plate. A plurality of bearing needles arranged in series one next to the other rolls between the axial inner sides of the bearing disks. These bearing needles are each held by a bearing cage in a uniform spacing relative to each other and together with the bearing cage form a needle-roller assembly.
In the assembly of such automatic transmissions, however, in practice it has been shown that the use of axial needle bearings in the provided bearing positions and the use of the carrier part supported by the axial needle bearings is associated with considerable time costs due to the relatively large number of individual parts and the necessary precision and therefore is very expensive. The usually manual assembly of the two axial needle bearings also has the risk that one of the axial needle bearings will be unintentionally left out or they will be installed on the wrong side of the carrier part to be supported and/or of the bearing disks due to their identical construction and size. This can result in faulty final assemblies that already cause faulty functions when the gearbox is started up or the different plate thicknesses of the bearing rings of the two axial needle bearings lead to axial stresses that result in increased wear of the axial needle bearings and thus to the premature failure of the gearbox when the automatic transmission is running.